Understanding economic analysis and cost-effectiveness of CT scan-guided, 3-dimensional, robotic-arm assisted lower extremity arthroplasty: a systematic review

Aim: The overall goal of this review was to examine the cost-utility of robotic-arm assisted surgery versus manual surgery. Methods: We performed a systematic review of all health economic studies that compared CT-based robotic-arm assisted unicompartmental knee arthroplasty, total knee arthroplasty and total hip arthroplasty with manual techniques. The papers selected focused on various cost-utility measures. In addition, where appropriate, secondary aims encompassed various clinical outcomes (e.g., readmissions, discharges to subacute care, etc.). Only articles directly comparing CT-based robotic-arm assisted joint arthroplasty with manual joint arthroplasty were included, for a resulting total of 21 reports. Results: Almost all twenty-one studies demonstrated a positive effect of CT scan-guided robotic-assisted joint arthroplasty on health economic outcomes. For studies reporting on 90-day episodes of costs, 10 out of 12 found lower costs in the robotic-arm assisted groups. Conclusion: Robotic-arm assisted joint arthroplasty patients had shorter lengths of stay and cost savings based on their 90-day episodes of care, among other metrics. Payors would likely benefit from encouraging the use of this CT-based robotic technology.

The Impact of Glucagon-Like Peptide-1 Agonists on Hip and Knee Arthroplasty and Perioperative Considerations

Glucagon-Like Peptide agonists have traditionally been used for glycemic control in diabetic patients. However, there has been a dramatic rise in their utilization for weight loss management. As such, arthroplasty surgeons will encounter an increasing number of patients on these medications, and therefore it is important to understand the implications of their use in the perioperative period. This review will describe the pharmacological actions of these medications as well as the impact on hip and knee arthroplasty patients, and considerations for perioperative management. Because of the rapid adaption and utilization of these drugs, the science is evolving at a fast pace. More and longer-term studies are needed to truly understand the impact of these medications on total joint arthroplasty utilization and in management of these patients in the perioperative period.

Preoperative Activity Level an Indicator of Postoperative Functional Outcomes with a Contemporary Revision Total Knee System

As the population requiring revision total knee arthroplasty (rTKA) grows, varying preoperative conditions may need to be considered when attempting to predict postoperative outcomes. Considering preoperative activity levels may help manage the expectations of patients. The purpose of this study was to analyze the outcomes of low- and high-activity subgroups of patients receiving a contemporary rTKA. One hundred and eighty-one rTKA patients enrolled in a prospective multicenter study were evaluated over a minimum follow-up of 2 years postoperatively. Patients were divided into two groups based on the preoperative activity level using the Lower Extremity Activity Scale. Patients scoring between 1 and 7 were classified as "Low Activity" (LA; N = 105) and patients scoring 8 to 18 were classified as "High Activity" (HA; N = 76). Clinical outcomes were evaluated, with an additional quality-of-life analysis completed utilizing SF-6D (6-dimension short form) scores obtained through a method described by Brazier et al and analyzed for effect size. There were no significant differences in age or body mass index between the groups. Postoperative improvement in both groups were similar in the Knee Society score (KSS), but the LA group showed larger increases in the KSS functional assessment at 6 months (16.2) and 2 years (34.8). There was a statistically significant effect (0.96, p = 0.0006) seen in the LA group at 1 year, in conjunction with a higher SF-6D outcome. The current study population displayed significant improvement in functional patient outcomes following rTKA regardless of preoperative activity level and function. Patients with lower preoperative activity levels demonstrated greater cumulative functional and quality-of-life improvements. This suggests that a lower preoperative activity level may be related to a poorly functioning knee and that rTKA has the potential to improve overall activity levels and function. Low preoperative function should not disqualify patients for rTKA.

Management of Primary Aggressive Tumors of the Knee

Primary bone sarcomas and aggressive benign bone tumors are relatively rare. It is essential to recognize features that are concerning for these aggressive tumors based on a patient's history, physical exam, and radiographs. Physicians and other health care providers should have a high suspicion for these tumors and promptly refer these patients to orthopaedic oncologists. A multidisciplinary, team-based approach is required to obtain an accurate diagnosis and provide comprehensive care. This review discussed the appropriate work-up, biopsy principles, relevant peri-operative medical management, and surgical treatment options for patients with aggressive primary bone tumors around the knee. Primary bone sarcomas (osteosarcoma and chondrosarcoma) and aggressive benign bone tumors (giant cell tumor, chondroblastoma, and chondromyxoid fibroma) that have a predilection to the distal femur and proximal tibia are the focus of this review.

Evaluation and Management of Intra-Articular Tumors of the Knee

Intra-articular tumors of the knee are most commonly benign. Overall, this is a relatively rare clinical presentation. The differential diagnosis includes pigmented villonodular synovitis, synovial chondromatosis, lipoma arborescens, synovial hemangioma, and very rarely primary sarcoma (synovial sarcoma being the most common). The clinical presentation for these conditions is usually non-specific, but radiographic and advanced imaging findings are able to differentiate some of these tumors. It is essential to obtain and send tissue specimens to pathology for histologic analysis to rule out a primary malignancy as a missed diagnosis can have grave implications on patient outcomes. This review summarized key aspects of diagnosis and treatment for these conditions.

Management of Pathologic Fractures around the Knee: Part 1-Distal Femur

Pathologic fractures secondary to metastatic disease are an increasingly prevalent problem. Such patients require multidisciplinary collaboration to optimize clinical outcomes. An established algorithm for clinical, laboratory, and radiographic work-up will ensure that each patient achieves the best outcome while avoiding catastrophic complications. Metastatic disease to the region of the knee is less commonly encountered than in other regions of the body, but it presents unique difficulties that merit discussion. Part one of this two-part article series will discuss the appropriate work-up of patients with suspected or impending pathologic fracture of the distal femur, highlight biopsy principles, address perioperative nonsurgical treatments that will optimize patient outcomes, and discuss available surgical treatment modalities.

Management of Pathologic Fractures around the Knee: Part 2-Proximal Tibia

Metastatic disease affecting the proximal tibia is rarer than disease affecting the femur; however, it presents unique challenges that the orthopaedic surgeon must address to ensure successful outcomes and return the patient to an ambulatory status. The essential workup for evaluating and treating these patients is addressed briefly in this review as a summary of the information is provided in part 1 of this series. Part 2 of this series will focus on the surgical treatment of these lesions, which can be complex and is not as well described in the literature. Procedures ranging from open reduction internal fixation with cement augmentation to complex endoprosthetic reconstruction can be employed to address proximal tibia metastatic disease. An awareness of these various treatment modalities allows the orthopaedic surgeon to plan the most effective operation for the patients under their care.

Benefits of CT Scanning for the Management of Knee Arthritis and Arthroplasty

This review investigated the potential value of computed tomography (CT) scans for the evaluation and management of knee arthritis and arthroplasty. Specifically, we evaluated the following: (1) assessment of arthritis within knee compartments, (2) patellofemoral joint assessment, (3) implant sizing prediction, (4) component alignment, (5) soft-tissue protection, and (6) potential concerns with radiation exposure. To compare if CT or X-ray imaging is more accurate and clinically relevant, a search was performed using Boolean search operators and terms: "CT," "radiograph," "joint alignment," "knee," and "arthroplasty," which yielded 661 results. Studies were evaluated based on (1) assessment of arthritis within knee compartments, (2) patellofemoral joint assessment, (3) implant sizing prediction, (4) component alignment, (5) soft-tissue protection, and (6) potential concerns with radiation exposure. Correlative and comparative analyses of imaging modalities to pre-, intra-, and postoperative clinical and patient-related factors were performed for the 63 included studies. CT scans were found to better detect medial and lateral arthritic changes, bony deformities, subchondral cysts, and cartilage losses. CT scans were shown to 99% accurately predict prosthetic sizes preoperatively. CT scans can also help better visualize surrounding anatomy, such as the posterior cruciate ligament, and have therefore been linked to better soft tissue protection during total knee arthroplasty. Although radiation is a potential concern, newer imaging protocols have comparable exposure to plain radiographs. Compared with plain radiographs, CT scans were found to be more accurate and provide more clinically relevant data. Therefore, the authors recommend the use of CT for the evaluation of certain patients with arthritis and for preoperative planning for knee arthroplasty.

Health Care Utilization and Payer Cost Analysis of Robotic Arm Assisted Total Knee Arthroplasty at 30, 60, and 90 Days

This study performed a health care utilization analysis between robotic arm assisted total knee arthroplasty (rTKA) and manual total knee arthroplasty (mTKA) techniques. Specifically, we compared (1) index costs and (2) discharge dispositions, as well as (3) 30-day (4) 60-day, and (5) 90-day (a) episode-of-care costs, (b) postoperative health care utilization, and (c) readmissions. The 100% Medicare Standard Analytical Files were used for rTKAs and mTKAs performed between January 1, 2016, and March 31, 2017. Based on strict inclusion-exclusion criteria and 1:5 propensity score matching, 519 rTKA and 2,595 mTKA patients were analyzed. Total episode payments, health care utilization, and readmissions, at 30-, 60-, and 90-day time points were compared using generalized linear model, binomial regression, log link, Mann-Whitney, and Pearson's chi-square tests. The rTKA versus mTKA cohort average total episode payment was US$17,768 versus US$19,899 (p < 0.0001) at 30 days, US$18,174 versus US$20,492 (p < 0.0001) at 60 days, and US$18,568 versus US$20,960 (p < 0.0001) at 90 days. At 30 days, 47% fewer rTKA patients utilized skilled nursing facility (SNF) services (13.5 vs. 25.4%; p < 0.0001) and had lower SNF costs at 30 days (US$6,416 vs. US$7,732; p = 0.0040), 60 days (US$6,678 vs. US$7,901, p = 0.0072), and 90 days (US$7,201 vs. US$7,947, p = 0.0230). rTKA patients also utilized fewer home health visits and costs at each time point (p < 0.05). Additionally, 31.3% fewer rTKA patients utilized emergency room services at 30 days postoperatively and had 90-day readmissions (5.20 vs. 7.75%; p = 0.0423). rTKA is associated with lower 30-, 60-, and 90-day postoperative costs and health care utilization. These results are of marked importance given the emphasis to contain and reduce health care costs and provide initial economic insights into rTKA with promising results.

Comparison of Knee Kinematics and Kinetics during Stair Descent in Single- and Multi-Radius Total Knee Arthroplasty

Despite continuing advances, nearly 20% of patients remain dissatisfied with their total knee arthroplasty (TKA) outcomes. Single-radius (SR) and multiradius (MR) TKA designs are two commonly used knee replacement designs based on competing theories of the flexion/extension axis of the knee. Our aim was to characterize stair descent kinematics and kinetics in SR and MR TKA subjects. We hypothesized that 1 year after TKA, patients who received SR TKA will more closely replicate the knee kinematics and kinetics of healthy age-matched controls during stair descent, than will MR TKA patients. SR subjects (n = 12), MR subjects (n = 12), and age-matched controls (n = 12) descended four stairs affixed to force platforms, while 10 infrared cameras tracked markers attached to the body to collect kinematic and kinetic data. Both patient groups had improvements in stair descent kinetics and kinematics at the 1-year postoperative time point. However, SR TKA subjects were indistinguishable statistically from age-matched controls, while MR TKA subjects retained many differences from controls. Similar to previous reports for level walking, the SR knee design performs closer to healthy controls than MR knees during stair descent. This study demonstrates that patients who receive SR TKA have more improved kinematic normalization during stair descent postoperatively than those who received an MR TKA.

Comparison of Knee Kinematics and Kinetics during Stair Ascent in Single-Radius and Multiradius Total Knee Arthroplasty

Traditionally total knee arthroplasty (TKA) design has been based on theories of the movement of the healthy knee joint. Currently, there are two competing theories on the flexion/extension axis of rotation of the knee with disparate radii of rotation, and thus differing movement patterns. The purpose of our study was to compare stair ascent kinematics and kinetics of single-radius (SR) and multiradius (MR) TKA subjects. We hypothesized that the knee kinematics and kinetics of SR TKA patients would more closely replicate healthy age matched controls during stair ascent than MR TKA patients, 1 year after TKA. Both patient groups had large improvements in biomechanical and clinical outcome measures following surgical intervention. However, the SR knee design performs closer to healthy controls than MR knees during stair ascent, supporting results that have been previously obtained for level walking. SR TKA subjects demonstrated reduced power production and sagittal moment compared with controls, albeit more than MR TKA subjects. This study demonstrates that patients who receive SR TKA have kinematics more closely aligned to normal patterns postoperatively than those who received an MR TKA. The power production and sagittal moment of the healthy controls most closely match previously published values of younger adults, SR TKA group most closely matches older adults, while the MR TKA group has lower power production and sagittal moments than either previously published age group. This strongly suggests that the biomechanical differences found in this study are evidence of functional deficiencies. Further research is needed to determine how these deficiencies progress with patient aging.

A 90-day episode-of-care cost analysis of robotic-arm assisted total knee arthroplasty

Aim: To evaluate 90-day episode-of-care (EOC) costs associated with robotic-arm assisted total knee arthroplasty (rTKA) versus manual TKA (mTKA). Patients & methods: TKA procedures were identified in Medicare 100% data. Accounting for baseline differences, propensity score matching was performed 1:5. 90-day EOC and index costs, lengths-of-stay, discharge disposition and readmission rates were assessed. Results: A total of 519 rTKA and 2595 mTKA were included. Overall 90-day EOC costs were US$2391 less for rTKA (p < 0.0001). Over 90% of patients in both cohorts utilized post-acute services, with rTKA accruing fewer costs than mTKA. Post-acute savings can be attributed to discharge destination. Conclusion: rTKA incurred an overall lower 90-day EOC cost versus mTKA. Savings were driven by fewer readmissions and an economically beneficial discharge destinations.

A 90-day episode-of-care cost analysis of robotic-arm assisted total knee arthroplasty

AIM

To evaluate 90-day episode-of-care (EOC) costs associated with robotic-arm assisted total knee arthroplasty (rTKA) versus manual TKA (mTKA).

PATIENTS & METHODS

TKA procedures were identified in Medicare 100% data. Accounting for baseline differences, propensity score matching was performed 1:5. 90-day EOC and index costs, lengths-of-stay, discharge disposition and readmission rates were assessed.

RESULTS

A total of 519 rTKA and 2595 mTKA were included. Overall 90-day EOC costs were US$2391 less for rTKA (p < 0.0001). Over 90% of patients in both cohorts utilized post-acute services, with rTKA accruing fewer costs than mTKA. Post-acute savings can be attributed to discharge destination.

CONCLUSION

rTKA incurred an overall lower 90-day EOC cost versus mTKA. Savings were driven by fewer readmissions and an economically beneficial discharge destinations.

Robotic-Arm Assisted Total Knee Arthroplasty Demonstrated Greater Accuracy and Precision to Plan Compared with Manual Techniques

This study determined if robotic-arm assisted total knee arthroplasty (RATKA) allows for more accurate and precise bone cuts and component position to plan compared with manual total knee arthroplasty (MTKA). Specifically, we assessed the following: (1) final bone cuts, (2) final component position, and (3) a potential learning curve for RATKA. On six cadaver specimens (12 knees), a MTKA and RATKA were performed on the left and right knees, respectively. Bone-cut and final-component positioning errors relative to preoperative plans were compared. Median errors and standard deviations (SDs) in the sagittal, coronal, and axial planes were compared. Median values of the absolute deviation from plan defined the accuracy to plan. SDs described the precision to plan. RATKA bone cuts were as or more accurate to plan based on nominal median values in 11 out of 12 measurements. RATKA bone cuts were more precise to plan in 8 out of 12 measurements (p ≤ 0.05). RATKA final component positions were as or more accurate to plan based on median values in five out of five measurements. RATKA final component positions were more precise to plan in four out of five measurements (p ≤ 0.05). Stacked error results from all cuts and implant positions for each specimen in procedural order showed that RATKA error was less than MTKA error. Although this study analyzed a small number of cadaver specimens, there were clear differences that separated these two groups. When compared with MTKA, RATKA demonstrated more accurate and precise bone cuts and implant positioning to plan.

Comparing the Efficacy of the Total Stabilizing and Posterior Stabilizing Knee Prostheses in Obese and Preobese Females: A Retrospective Cohort Study

Obesity is associated with increased surgical complications that may lead to suboptimal total knee arthroplasty (TKA) outcomes. Additionally, females exhibit increased rates of severe, clinical osteoarthritis OA, along with increased ligamentous laxity. Therefore, obese females present a particularly challenging case for TKA with increased joint loads coupled with a propensity for instability. This study retrospectively analyzed knee range of motion and stability of one TKA designs with two different degrees of polyethylene conformity in the obese female population. The implants (Stryker Triathlon total stabilizing [TS] and Stryker Triathlon posterior stabilizing [PS]) differ in their level of constraint, with the TS being more constrained. We hypothesized that the TS implants would be associated with improved functional outcomes in the obese female population, secondary to increased coronal stability to offset the ligamentous laxity. Of 482 knees reviewed, 173 met the inclusion criteria of: female, body mass index (BMI) ≥ 25, receiving TS (N = 93), or PS (N = 8). Primary knee outcome measures were: active flexion, passive flexion, active extension, passive extension, and stability at 0° and 30° flexion. These factors were statistically analyzed at preop, 2-week, 6-week, 3-month, and 1-year time points. Preoperatively, the TS cohort was significantly higher in BMI and knee laxity, potentially starting this cohort at a functional disadvantage. Postoperatively, the TS implant was associated with a statistically significant early improvement in active and passive knee extension. There was no longer any significant difference in knee laxity postop. Our data support the hypothesis that obese females may benefit from the increased stability afforded by the TS design.

Population-based contracting (population health): part II

Modern healthcare contracting is shifting the responsibility for improving quality, enhancing community health and controlling the total cost of care for patient populations from payers to providers. Population-based contracting involves capitated risk taken across an entire population, such that any included services within the contract are paid for by the risk-bearing entity throughout the term of the agreement. Under such contracts, a risk-bearing entity, which may be a provider group, a hospital or another payer, administers the contract and assumes risk for contractually defined services. These contracts can be structured in various ways, from professional fee capitation to full global per member per month diagnosis-based risk. The entity contracting with the payer must have downstream network contracts to provide the care and facilities that it has agreed to provide. Population health is a very powerful model to reduce waste and costs. It requires a deep understanding of the nuances of such contracting and the appropriate infrastructure to manage both networks and risk. Cite this article: Bone Joint J 2017;99-B:1431-4.

Episodic payments (bundling): PART I

Episodic, or bundled payments, is a concept now familiar to most in the healthcare arena, but the models are often misunderstood. Under a traditional fee-for-service model, each provider bills separately for their services which creates financial incentives to maximise volumes. Under a bundled payment, a single entity, often referred to as a convener (maybe the hospital, the physician group, or a third party) assumes the risk through a payer contract for all services provided within a defined episode of care, and receives a single (bundled) payment for all services provided for that episode. The time frame around the intervention is variable, but defined in advance, as are included and excluded costs. Timing of the actual payment in a bundle may either be before the episode occurs (prospective payment model), or after the end of the episode through a reconciliation (retrospective payment model). In either case, the defined costs over the defined time frame are borne by the convener. Cite this article: Bone Joint J 2017;99-B:1280-5.

Robotic-Arm Assisted Total Knee Arthroplasty Demonstrated Soft Tissue Protection

INTRODUCTION

While total knee arthroplasty (TKA) procedures have demonstrated clinical success, occasionally intraoperative complications can occur. Collateral or posterior cruciate ligament injury, instability, extensor mechanism disruption, and tibiofemoral or patellofemoral dislocation are among a few of the intraoperatively driven adverse events prevalently ranked by The Knee Society. Robotic-arm assisted TKA (RATKA) provides a surgeon the ability to three-dimensionally plan a TKA and use intraoperative visual, auditory, and tactile feedback to ensure that only the desired bone cuts are made. The potential benefits of soft tissue protection in these surgeries need to be further evaluated. The purpose of this cadaver study was to assess the a) integrity of various knee soft tissue structures (medial collateral ligament [MCL], lateral collateral ligament [LCL], posterior cruciate ligament [PCL], and the patellar ligament), as well as b) the need for tibial subluxation and patellar eversion during RATKA procedures.

MATERIALS AND METHODS

Six cadaver knees were prepared using RATKA by a surgeon with no prior clinical robotic experience. These were compared to seven manually performed cases as a control. The mean Kellgren-Lawrence score was 2.8 (range, 0 to 4) in RATKA and 2.6 (range, 1 to 4) in the manual cohort. The presence of soft tissue damage was assessed by having an experienced surgeon perform a visual evaluation and palpation of the PCL, MCL, LCL, and the patellar ligament after the procedures. In addition, leg pose and retraction were documented during all bone resections. The amount of tibial subluxation and patellar eversion was recorded for each case.

RESULTS

For all RATKA-assisted cases, there was no visible evidence of disruption of any of the ligaments. All RATKA cases were left with a bone island on the tibial plateau, which protected the PCL. Tibial subluxation and patella eversion were not required for visualization in any RATKA cases. In two of the seven MTKA cases, there was slight disruption noted of the PCL, although this did not lead to any apparent change in the functional integrity of the ligament. All MTKA cases required tibial subluxation and patellar revision to achieve optimal visualization.

DISCUSSION

Several aspects of soft tissue protection were noted during the study. During bone resections, the tibia in RATKA procedures did not require subluxation, which may reduce ligament stretching or decrease complication rates. Potential patient benefits for short-term recovery and decreased morbidity to reduce operative complications should be studied in a clinical setting. Since RATKA uses a stereotactic boundary to constrain the sawblade, which is generated based on the implant size, shape, and plan, and does not have the ability to track the patient's soft tissue structures, standard retraction techniques during cutting are recommended. Therefore, the retractor placement and potential for soft tissue protection needs to be further investigated. RATKA has the potential to increase soft tissue protection when compared to manual TKA.

Normothermia in Arthroplasty

BACKGROUND

Since the initial design of surgical theatres, the thermal environment of the operating suite itself has been an area of concern and robust discussion. In the 1950s, correspondence in the British Medical Journal discussed the most suitable design for a surgeon's cap to prevent sweat from dripping onto the surgical field. These deliberations stimulated questions about the effects of sweat-provoking environments on the efficiency of the surgical team, not to mention the effects on the patient. Although these benefits translate to implant-based orthopedic surgery, they remain poorly understood and, at times, ignored.

METHODS

A review and synthesis of the body of literature on the topic of maintenance of normothermia was performed.

RESULTS

Maintenance of normothermia in orthopedic surgery has been proven to have broad implications from bench top to bedside. Normothermia has been shown to impact everything from nitrogen loss and catabolism after hip fracture surgery to infection rates after elective arthroplasty.

CONCLUSION

Given both the physiologic impact this has on patients, as well as a change in the medicolegal environment around this topic, a general understanding of these concepts should be invaluable to all surgeons.

The Halo Effect: An Unintended Benefit of Care Pathways

The objective of this study was to determine if implementation of a simplified care pathway for total knee arthroplasty (TKA) would affect outcomes of total hip arthroplasty (THA) patients in the same health care system. Data were collected from a total of 5,095 consecutive THA patients in the year before and 2 years after implementation of the care pathway for TKA patients. Postimplementation increases were observed in both early activity (p < 0.0001) and continuous urinary catheter avoidance (p < 0.0001) among THA patients. These improvements in protocol adherence were associated with decreased complications (p < 0.0001), fewer 30-day readmissions (p < 0.0019), and decreased hospital length of stay (p < 0.0001). Based on these results, the implementation of a simplified care pathway for TKA patients can also improve outcomes for THA patients in the same health care system.

Contracting Strategies for Arthroplasty-Bundles to Population Health

Orthopedics, and especially total joint replacement (TJR), is growing in payer prominence due to large projected increases in volume. The unsustainability of the fee-for-service payment system has lead Centers for Medicare and Medicaid Services to employ new value and risk-based contracting strategies on a population health basis and on an episode of care basis, with programs such as the Bundled Payment for Care Improvement program and the Comprehensive Care for Joint Replacement program. These trends are forcing hospitals and physicians to align to improve quality and reduce costs through new structures such as Accountable Care Organizations, comanagement programs, and gainsharing. Bundled payment programs are typically used to align specialists such as orthopedic surgeons and TJR has been on the forefront of bundled payment contracting strategies. Bundled payment programs with commercial insurers can create additional opportunities, as do commercial bundled payment contracts for TJR performed on an outpatient basis. As these programs are now becoming mandatory, surgeons must understand the structural aspects of these arrangements and the levers available to optimize the likelihood of success.

Bilateral Symmetrical Comparison of Femoral and Tibial Anatomic Features

BACKGROUND

Variability in morphologic features of the human lower extremity within and across populations has been reported, but limb asymmetry within individuals is often overlooked. For example, in 19 studies of version of the lower extremity in the literature, 6 document asymmetry in the population, but none of these reports document asymmetry in an individual. The aim of this study was to identify the (a)symmetry and quantify variability in the tibiae and femora of matched pairs of limbs. More specifically, using a computed tomography scan database tool, we (1) identified (a)symmetry between paired left and right legs for angulation, version, and alignment features and (2) calculated the percentage of paired limbs with >1° of (a)symmetry for each evaluated parameter.

METHODS

Computerized axial tomographic scans (<1.0 mm slices) from bilateral lower limbs of 361 skeletally mature subjects without bone pathology were prospectively acquired. Bones were segmented and morphologic features were measured.

RESULTS

Angular features are symmetric left to right, but rotational features are not, with 7° of mean asymmetry in femoral anteversion (range: 0°-23°) and 3° of asymmetry in tibial version (range: 0°-8°).

CONCLUSIONS

This study disproves the hypothesis that human limbs are absolutely symmetric, confirming instead that there is asymmetry in version between left and right paired limbs. Surgeons strive for symmetry in lower extremity reconstruction, and they often compare side to side in outcome studies, believing that normal limbs are absolutely symmetric when this is not necessarily true. These assumptions concerning lower extremity symmetry need to be reassessed.

A Patient Blood Management Program in Prosthetic Joint Arthroplasty Decreases Blood Use and Improves Outcomes

The objective of this study was to determine if a Patient Blood Management (PBM) program implemented for patients undergoing THA or TKA would result in a decrease in the percentage of patients transfused PRBCs and improve outcomes. Decision support, a key driver for this program, was built into the electronic medical record. This retrospective cohort study included 12,590 patients and demonstrated a 44% decrease in the percentage of patients transfused. This was associated with a significant reduction in complications, 30 day readmissions and HLOS. A PBM program for patients undergoing prosthetic joint arthroplasty for primary and revision total hip and knee arthroplasty results in fewer transfusions and is associated with improved outcomes.

Quantitative, Comparative Assessment of Gait Between Single-Radius and Multi-Radius Total Knee Arthroplasty Designs

Gait of single-radius (SR, n=16) and multi-radius (MR, n=16) posterior stabilized total knee arthroplasties was compared, along with controls (n=16), pre-op and 1 year post-op. Computer navigation and standard order sets controlled confounding variables. Post-operatively, SR knees did not differ from controls while MR knees continued to differ in important knee kinetic and kinematic properties. MR knees remained more extended (P=0.019) and had decreased power absorption (P=0.0001) during weight acceptance compared to the SR knees. Both surgical groups had similar KSS for Knee Scores (P=0.22) and Function Scores (P=0.58). The significant biomechanical differences are likely influenced by patella-femoral moment arm geometry and changing ligament laxity throughout the active range of motion.

Wear and loosening in total knee arthroplasty: a quick review

Wear and osteolysis are common problems that often require revision surgery following total knee arthroplasty (TKA). Wear rates can be reduced through proper implant positioning and the use of modern, highly cross-linked polyethylene liners. More research is needed to identify medications that could prevent or treat the bone loss associated with osteolysis. Bone defects resulting from osteolysis can be managed with a variety of bone-preserving strategies and often require the use of structural augmentation, either in the form of bulk allografts or metal augments. Recently, porous metal augments such as tantalum cones have gained popularity among surgeons performing revision TKA for osteolytic bone defects with promising early clinical results. A megaprosthesis with a rotating hinge device may be used in salvage cases for severe bone deficiencies.

Early postoperative complications after total hip arthroplasty: current strategies for prevention and treatment

Total hip arthroplasty is a highly successful treatment for end-stage arthritis that substantially improves patients' symptoms and function. Unfortunately, complications in the early postoperative period are inevitable, even in procedures performed by experienced surgeons using careful surgical techniques. Current strategies to prevent and effectively manage the most common early complications after total hip arthroplasty, including periprosthetic joint infection, instability, leg-length inequality, and periprosthetic femoral fracture, are discussed.

A simplified pathway for total knee arthroplasty improves outcomes

Care pathways for total knee arthroplasty (TKA) demonstrate improved quality and utilization outcomes. Standardizing these processes over large systems is difficult due to the variability of practice patterns and the complexity of multistep pathways. A simplified approach to this process focusing on early activity and avoidance of continuous urinary catheters was performed to overcome these perceived barriers for implementing a system-wide care pathway. Data were collected from a total of 6,154 consecutive patients during the time period of 1 year before and 1 year after implementation of a pathway focusing on two key drivers: early activity and continuous urinary catheter avoidance. Patients included were adults admitted for elective primary TKA. A composite score was calculated based on the successful completion of the two key drivers. Outcome measures were tracked before and after implementation. Following implementation of a simplified TKA care pathway, there was a significant increase in the composite score with increases attributable to both increased early activity (p < 0.0001) and continuous urinary catheter avoidance (p < 0.0001). This improvement in composite score was associated with a significant decrease in hospital length of stay (HLOS) (p < 0.0001), costs (p < 0.0001), complications (p < 0.0001), and 30-day readmissions (p < 0.0106). A fixed-effect model analysis demonstrated early activity was associated with improvements in HLOS (p < 0.0001), complications (p = 0.0240), and 30-day readmissions (p = 0.0046). Avoidance of a continuous urinary catheter was associated with improvements in HLOS (p = 0.0001), costs (p < 0.0001), complications (p = 0.0006), and 30-day readmissions (p = 0.0008). A simplified care pathway for TKA focusing on early activity and continuous urinary catheter avoidance is associated with improved complications, costs, HLOS, and 30-day readmissions.

Makoplasty and the accuracy and efficacy of robotic-assisted arthroplasty

In comparison with standard surgical techniques robotic-assisted surgery has the advantages of increased surgical accuracy, reproducibility, optimization of component position, and improved patient outcomes in unicompartmental knee arthroplasty (UKA) and total hip arthoplasty (THA) procedures. The MAKO Tactile Guidance System (TGS; MAKO Surgical Corp, Fort Lauderdale, FL) facilitates robotic-assisted arthroplasty procedures currently implemented in many operating rooms. The benefits of this technology are evident, but have not been shown to improve patient outcomes and justify the added financial burden imposed. Further research is needed to determine if this technological advancement will translate into improvements in longevity and clinical outcomes.

Differences between midvastus and subvastus TKA surgical approaches in the tasks of sitting and standing

The mini-midvastus (MV) approach to total knee arthroplasty (TKA) minimizes damage to the extensor mechanism; however, the mini-subvastus (SV) approach is designed to avoid such damage. Quadriceps weakness following TKA can have a significant impact on the activities of daily living, particularly stand-to-sit down (STSD) and sit-to-stand up (STSU) activities. Fifty-three subjects diagnosed with primary osteoarthritis and scheduled to undergo TKA were randomized to receive an MV or SV surgical approach and were given identical postoperative orders. Compared with age-matched controls, the SV group had a quicker return of normal peak knee extension moment during STSU, whereas the MV group had a quicker return of normal movement patterns in hip, knee, and ankle parameters during STSD yet represented the higher functioning subjects as more MV subjects had difficulty completing the task as instructed. Considering both movements are required for daily living, neither surgical group was found to have a significant advantage over the other in functional outcome through 6 months post-TKA.

Differences between standard and minimally invasive parapatellar surgical approaches for total knee arthroplasty in the tasks of sitting and standing

Minimally invasive total knee arthroplasty (TKA) aims to enhance functional recovery and minimize trauma to the knee extensor mechanism through quadriceps sparing techniques. Few have studied the effect of TKA surgical approach on activities of daily living. Stand-to-sit-down (STSD) and sit-to-stand-up (STSU) activities are challenging for patients in constrained scenarios where upper body support is limited. In this study, 60 subjects diagnosed with primary osteoarthritis undergoing TKA were randomized to receive the standard parapatellar (SP) or mini-parapatellar (MP) surgical approach performed using computer navigation. All received identical postoperative orders, hospitalization, and physical therapy. Before surgery and at 2, 4, and 6 months postoperatively, the STSD and STSU kinetics and kinematics showed differences for both groups in comparison with controls, but the two were essentially indistinguishable throughout all time points.

Role of total knee arthroplasty approaches in gait recovery through 6 months

Four major approaches to total knee arthroplasty (TKA) exist: standard parapatellar, subvastus, midvastus, and mini-parapatellar. Research has shown that there may be some benefit to patients when minimally invasive approaches are employed. However, research has not shown whether the minimally invasive approaches are beneficial for restoring patients' gait when compared against those of healthy age-matched subjects. This study has compared the effect of the four surgical approaches using computer navigation on recovery of gait at 2, 4, and 6 months. Although some statistically significant differences exist among surgical approaches at specific points of the gait cycle, results demonstrate that no approach is superior to another in restoring patients' gait across the entire gait cycle.

Valgus bracing affords short-term treatment solution across walking and sit-to-stand activities

Since activities of daily living do not exist in isolation this prospective study examined biomechanical function during level walking and sit-to-stand activities over two months of brace use by subjects with varying grades of knee osteoarthritis. Kinematic and kinetic data were collected using infrared cameras and force platforms; clinical scores compared perceived and measured functional effects. There was no significant change in pain for any grades of OA but activity levels were significantly higher at one month in the moderate OA grades and at two months for the low OA grades. Mechanical constraints and changes in movement strategies were consistent across tasks and OA grade. This study provides valuable data for further studies aimed at refining the use and optimization of valgus bracing efficacy.

Improving initial acetabular component stability in revision total hip arthroplasty calcium phosphate cement vs reverse reamed cancellous allograft

A reproducible retroacetabular defect was created bilaterally in 9 cadaver pelves. The defects were filled with either an injectable, bioresorbable, calcium phosphate cement, or reverse-reamed cancellous allograft. An uncemented acetabular shell was impacted, followed by the placement of an appropriate liner. The pelves were then sectioned, and each half was loaded in a material testing machine to simulate walking on the construct over a several week period. The cement-filled defects lasted a greater number of cycles before failure and had greater cup stability and stiffness. The use of resorbable bone void filler for retroacetabular defects shows promise in this biomechanical analysis. Long-term clinical follow-up is warranted to track osseointegration of the implant and restoration of bone stock between this and other clinically accepted surgical techniques.

Revision total knee arthroplasty: what the practicing orthopaedic surgeon needs to know

The number of revision total knee arthroplasties (TKAs) continues to steadily increase. The evaluation of painful and revision TKAs may be challenging for the general orthopaedic surgeon, but a standardized, systematic approach to each patient will allow predictable surgical outcomes. This approach begins with a consistent and thorough preoperative patient evaluation. Revision surgery should not be performed until the etiology of failure of the index arthroplasty is known. The possibility of infection in the revision setting also must be considered because this complication will drastically alter the treatment algorithm. Adjunctive techniques, including the quadriceps snip, the medial collateral ligament slide, and the tibial tubercle osteotomy, can greatly enhance surgical exposure and the efficient removal of components in revision TKAs. A thorough knowledge of the reconstructive options for replacing bone loss is crucial, and the availability of appropriate revision instrumentation is required for surgical efficiency. A concise diagnostic algorithm coupled with clear reconstructive principles will allow more efficient and confident management of a patient with a failed TKA.

Secure tracks device improves functional recovery and pain after total knee arthroplasty: a prospective, randomized, pilot study

This prospective, randomized study compares functional outcomes between a novel support device (Secure Tracks™) and a standard walker following unilateral total knee replacement. Thirty patients were randomized for the study; 15 walker patients (70.7±6.4 yrs) and 15 Secure Track patients (68.2±6.7 yrs) (p=0.31). Total distance walked during all therapy sessions was nearly two times greater in the Secure Track (2,332 ft) than with the walker (1,241 ft)(p=.053). This trend began on the day of surgery (275 ft vs. 176 ft, p<.069) and was statistically significant by the following morning (287 ft vs. 151 ft, p=.019). Patients in the Secure Track spent a greater amount of time up and ambulating with the therapists in all sessions (.006<p>.30). At the first clinical follow-up, patients that had walked in the Secure Track completed the timed up and go test (TUG), a predictor of fall risk, 3 seconds faster than the standard rehabilitation group (9.6 vs. 12.9 seconds, p<.091). The novel therapy patients demonstrated significantly greater pain relief following the TUG test (p=.005). This study demonstrates that the choice of support device can increase patient ambulation following surgery, which will in turn improve functional outcomes and pain relief.

Gait and stair function in total and resurfacing hip arthroplasty: a pilot study

Standard total hip arthroplasty (THA) is the established surgical treatment for patients older than 65 years with progressive osteoarthritis but survivorship curves wane in patients younger than 50. Resurfacing hip arthroplasty (RHA) is an alternative for younger, active patients reportedly providing superior range of motion. Quantitative investigation of functional recovery following arthroplasty may elucidate limitations that aid in device selection. Although limited long-term kinematic data are available, the early rate of recovery and gait compensations are not well described. This information may aid in refining rehabilitation protocols based on limitations specific to the implant. We presumed hip motion and forces for subjects receiving RHA are more similar to age-matched controls during physically demanding tasks, such as stair negotiation, at early time points than those for THA. In a pilot study, we quantified walking and stair negotiation preoperatively and 3 months postoperatively for seven patients with RHA (mean age, 49 years), seven patients with standard THA (mean age, 52 years), and seven age-matched control subjects (mean age, 56 years). Although both treatment groups demonstrated trends toward functional recovery, the RHA group had greater improvements in hip extension and abduction moment indicating typical loading of the hip. Further investigation is needed to determine if differences persist long term or are clinically meaningful.

Pathologic femoral neck fractures in children

Pathologic fractures in children occur in a variety of malignant and benign pathologic processes. Pediatric pathologic femoral neck fractures are particularly rare. Until now, all reported cases have been isolated cases, small series, or cases reported in series of adult pathologic hip fractures. The present article is the first report of a relatively large series of pathologic femoral neck fractures in a pediatric population. We identified pathologic femoral neck fractures, including 2 basicervical fractures, in 15 children (9 boys, 6 girls) ranging in age from 18 months to 15 years (mean age, 9 years) and treated between 1960 and 2000. The pathologic diagnoses were fibrous dysplasia (5 children), unicameral bone cyst (2), Ewing's sarcoma (2), osteomyelitis (2), leukemia (1), rhabdomyosarcoma (1), osteogenesis imperfecta (1), and osteopetrosis (1). Treatment methods, including time to reduction and fixation, were reviewed in detail. One patient was lost to follow-up. All others were followed until union; mean long-term follow-up was 7 years (range, 1-16 years). All patients ultimately went on to union. Mean time to union was 19 weeks (range, 5-46 weeks). However, 2 patients died before 2 years. There was a 40% complication rate, with limb-length discrepancy being the most common (4 children). No patient developed avascular necrosis. Pathologic femoral neck fractures are rare in children. Pediatric patients who present with a pathologic hip fracture are at significant risk for complications. Physicians and family should be alerted to the prolonged course involved in treating these fractures to union.

Accuracy of emergency room physicians' interpretation of elbow fractures in children

Elbow fractures in children can be difficult diagnoses for inexperienced physicians to make. The purpose of this prospective study was to determine the accuracy of radiograph interpretation of elbow fractures in children by emergency room (ER) physicians. Thirty fractures were analyzed. The ER physician's radiograph interpretation was compared to the final interpretation by the treating staff pediatric orthopedic surgeon. Accuracy rates were determined for overall agreement and by fracture subtype. Overall accuracy of ER physicians' interpretation was 53% (16/30). This study underscores the importance of educating ER physicians and residents in children's fracture interpretation to optimize patient outcomes. Orthopedists need to be vigilant when taking care of these patients to prevent unnecessary complications.

Highly cross-linked polyethylene in total knee arthroplasty: in the affirmative

Polyethylene bearing failure has been cited as one of the leading causes of knee arthroplasty revision surgery. In 1998, highly cross-linked polyethylene was introduced for clinical use in total hip arthroplasty. Altered mechanical properties in first-generation highly cross-linked polyethylene did exhibit clinical failures, such as post fractures in total knee arthroplasty. Remelting alters the integrity of polyethylene. Some approaches to mitigate this include mechanical deformation, vitamin E incorporation, and sequential irradiation and annealing. Forces and stresses in total knee arthroplasty differ substantially from the wear mechanisms and forces seen in total hip arthroplasty. There is now considerable interest in the clinical use of highly cross-linked polyethylene for the knee. The use of sequentially annealed, highly cross-linked polyethylene, based on bench top data, appears to be promising for use in total knee arthroplasty. One should be aware that all highly cross-linked polyethylenes are not manufactured, nor processed, in the same manner. Marked and significant differences may exist between products.

Biomechanical strength of the Peri-Loc proximal tibial plate: a comparison of all-locked versus hybrid locked/nonlocked screw configurations

OBJECTIVE

The purpose of this study was to compare the biomechanical properties of a contoured locking plate instrumented with either an all-locked or hybrid locked/nonlocked screw construct in a proximal metaphyseal fracture of the tibia (AO 41-A3.2).

METHODS

A standardized proximal metaphyseal wedge osteotomy (AO 41-A3.2) was created in five pairs of cadaveric tibia. Each pair was randomly instrumented with either an all-locked or combination locked/nonlocked screw construct using a locked contoured periarticular plate (Peri-Loc periarticular locked plating system, Smith & Nephew, Memphis, TN). Vertical subsidence (irreversible deformation) and deflection (reversible deformation) in each pair were analyzed and compared. Load to failure, defined by complete fracture gap closure, was also determined.

RESULTS

There was no statistically significant difference in vertical subsidence (P = 0.19) or deflection (P = 0.19) of the proximal tibia between the all-locked and combination locked/nonlocked screw construct with increasing levels of cyclical axial load from 200 to 1200 N. Failure occurred at a mean value of 2160 N in the locked group and 1760 N in the hybrid group (P = 0.19); the failure mode was plate bending in all specimens.

CONCLUSIONS

The results indicate that the use of compression screws with locked screws in this particular construct allows a similar amount of irreversible and reversible deformation in response to an axial load when compared to an all-locked screw construct. This suggests that there is no statistically significant difference in the stability in fixation between the two methods, allowing the surgeon the freedom to choose the appropriate screw combination unique to each fracture.

Comparison of intramedullary nailing and external fixation knee arthrodesis for the infected knee replacement

We analyzed knee arthrodesis for the infected total knee replacement (TKR) using two different fixation techniques. Patients undergoing knee arthrodesis for infected TKR were identified and rates of successful fusion and recurrence of infection were compared using Cox proportional hazard models. Eighty-five consecutive patients who underwent knee arthrodesis were followed until union, nonunion, amputation, or death. External fixation achieved successful fusion in 41 of 61 patients and was associated with a 4.9% rate of deep infection. Fusion was successful in 23 of 24 patients with intramedullary (IM) nailing and was associated with an 8.3% rate of deep infection. We observed similar fusion and infection rates with the two techniques. Thirty-four patients (40%) had complications. Knee arthrodesis remains a reasonable salvage alternative for the difficult infected TKR. Complication rates are high irrespective of the technique, and one must consider the risks of both nonunion and infection when choosing the fixation method in this setting. IM nailing appears to have a higher rate of successful union but a higher risk of recurrent infection when compared with external fixation knee arthrodesis.

LEVEL OF EVIDENCE

Level III, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Femoral neck fractures in pediatric patients: 30 years experience at a level 1 trauma center

Femoral neck fractures in children are severe injuries associated with the potentially disastrous complication of femoral head osseous necrosis. Our primary goal was to identify what factors contribute to the occurrence of femoral head osteonecrosis in skeletally immature patients with femoral neck fractures. We evaluated a large consecutive series of pediatric patients with femoral neck fractures. Between 1970 and 2000, 20 patients with a mean age of 11 years (range, 4-15 years) with femoral neck fractures were identified. All traumatic epiphyseal, transcervical, and basicervical (Types I, II, and III) fractures were included. There were 14 male patients and six female patients. The mean followup was 7 years (range, 1-28 years). Timing of surgery, type of fixation, and quality of reduction were analyzed with respect to the primary outcome measure-radiographic evidence of femoral head osteonecrosis. Eighteen of 20 hip fractures healed without complication; all had good or excellent reductions. Two patients had osteonecrosis develop; both had fair or poor reductions. Five patients were treated more than 48 hours after injury, including the two patients who had osteonecrosis develop. The mean time to fixation for the remaining patients was 12 hours. There was no relationship between capsular decompression and osteonecrosis development. Quality of reduction and timing of reduction influenced the risk of osteonecrosis.

Locking plate fixation for proximal humeral fractures: initial results with a new implant

Treatment of proximal humeral fractures remains controversial, with multiple reported techniques and variable results. Recently, locking plates have become available for fixation of osteopenic and comminuted fractures. This study reports our initial experience with a new locking plate designed specifically for proximal humeral fractures. We observed 16 patients until union or revision with a mean of 12 months' follow-up. Of the 16 patients, 9 had high-energy injuries. There were nine 3-part, five 2-part, and two 4-part fractures. Twelve of sixteen patients healed without complications. There were 4 nonunions; all occurred in patients with 3-part fractures with metadiaphyseal comminution, 3 of whom were heavy smokers. In patients with united fractures, mean elevation was 132 degrees and mean external rotation was 43 degrees, with mean internal rotation to T11. Locking plate fixation achieved union in 75% of patients in this series. Risk factors for delayed union or nonunion included comminution, smoking, and 3-part fractures. These fractures remain challenging despite the availability of locked plating systems.